Foldable structure



Feb. 14, 1939. y F. c. VANCE FOLDABLE STRUCTURE Filed Aug. ll, 1937 5Sheets-Sheet l IIN.. Iiwi Qm @Wn wh@ v @mmv gym/umm Feb. 14, 1939. f FC, VANCE 2,147,564

FOLDABLE STRUG TURE Filed Aug. l1, 1937 I l 5 Sheets-Sheet 2 5sheets-sheet 3 Filed Aug. 11, 1957 www@ Feb. 14, 1939. F. C, VANCEr2,147,564

FOLDABLE STRUCTURE Filed Aug. ll, 195'? 5 Sheets-Sheet 4 Feb. 14, 1939.F. c. vANcE y y FOLDABLE STRUCTURE 5 Sheets-Sheet 5 Filed Aug. ll, 1937Patented Feb. 14, 1939 PATENT CFFICE roLDABLE STRUCTURE Forrest C.Vance, Champaign, Ill.; Ella M.

Vance executrix of said Forrest G. Vance, de-

ceased Application August 11, 1937, Serial No. 158,621

1 Claim.

This invention relates to a new and useful improvement in foldablestructures, more particularly, to a structure of such class designed foruse as foldable grandstands in gymnasiums, public halls, at courts andplaying fields, and of that type including a plurality of longitudinallyextending seats, each capable of holding a number of persons, the seatswhen in use being disposed one below and in advance of the other andeach being associated with a corresponding foot board or foot rest.

The invention hasY for its object to provide, in a manner as hereinafterset forth, a foldable and extendible structure for the purpose referredto which may be expeditiously folded and extended at will and, whenfolded, will be arranged in a compact manner and occupy a relativelysmall area.

A further object of the invention is to provide, in a manner ashereinafter set forth, a foldable structure capable of being arranged atany desired point with respect to a playing field or court and out ofthe way of the athletes on the eld and court, and further capable ofbeing extended to constitute' a grandstand formed with a step-likearrangement of seats, and still further of being expeditiously folded ina compact manner to occupy a relatively small area.

A further object of the invention is to provide, in a manner ashereinafter set forth, a structure for the purpose referred to includingseats supported by uprights provided at their lower ends with rollers,and to further provide the structure with tracks upon which theserollers operate so as to prevent any twisting strain being applied tothe seats when the structure is extended or folded.

A further object of the invention is to provide, in a manner ashereinafter set forth, a structure for the purpose referred to includinga sectional base capable of being folded and extended and with the baseincluding track sections for endwise aligning when the base is extended.

A further object of the invention is to provide, in a manner ashereinafter set forth, a structure for the purpose referred to includingfoot boards or foot rests which will be supported entirely from the baseof the structure, when the latter is in its extended position.

Further objects of the invention are to provide, in a manner ashereinafter set forth, a foldable and extendible structure for thepurpose referred to which is comparatively simple in its constructionand arrangement, strong, durable, thoroughly efficient in the useintended thereby, conveniently extended and folded when occasionrequires, readily assembled and comparatively inexpensive to' set upwith respect to structures now employed for the same purpose.

With the foregoing and other objects which may hereinafter appear, theinvention consists of the novel construction, combination andarrangement of parts as will be more specifically referred to andillustrated in the accompanying drawings wherein is shown embodiments ofthe 10 invention, but it is to be understood that changes, variationsand modifications may be resorted to which fall within the scope of theinvention as claimed.

In the drawings:

Figure l is a longitudinal sectional view of the foldable structureextended,

Figure 2 is a longitudinal sectional view of the structure when folded,

Figure 3 is a fragmentary view broken away in top plan, of the base orfloor of the foldable structure upon an enlarged plan.

Figure 4 is a fragmentary view in longitudinal section of the base orHoor of the foldable structure, 25

Figure 5 is a sectional detail illustrating the construction of thetrack elements employed,

Figure 6 is a fragmentary View in longitudinal section illustrating thestructure partly folded, v

Figure '7 is a fragmentary view in front elevation of the foldablestructure when extended,

Figure 8 is an end elevation of a modified form of foldable structurewhen folded and with the seat members and foot boards in transverseseotion, 35

Figure 9 is a frangmentary view in front elevation of the structureshown in Figure 7 extended,

Figure 10 is a longitudinal sectional view of the modified form of thefoldable structure when extended, and

Figure 11 is a fragmentary View in longitudinal section of the modifiedform of the folding structure when the latter is partly extended. 45

With reference to Figures 1 to '7 both inclusive, the foldable andextendible structure which is termed a grandstand includes seat membersand foot boards or rests of any desirable length and said members andboards will be of like length. 50 As illustrated the grandstand,indicated generally at I 2 is shown by way of example as including fiveseat members and four foot boards or rests. It is to be understood thatthe number of seat members and foot boards may be as de- 55 sired, butthe nrunber of foot boards will be one less than the number of the seatmembers.

The grandstand I2 includes a set of spaced parallel vertically disposedstationary rear sup ports I3 of any suitable number provided withsuperposed means as at I4 for -detachably connecting them to and spacedforwardly from a wall or fence I5. As shown the means I4 is in the formof an angle-shaped bracket.

The grandstand I2 includes a set of spaced parallel vertically disposedslidable supports YI5 corresponding in number to that of the supportsI3. The supports IS are of less height than, arranged forwardly of andalign with the supports I3.

The grandstand I2 includes a set of spaced parallel vertically disposedslidable supports I'I corresponding in number to that of the supportsI6. The supports I are of less height than, arranged forwardly of, andalign with the supports I6.

The grandstand I2 includes a set of spaced parallel vertically disposedslidable supports I8 corresponding in number to that of the supports il.The supports I8 are of less height than, arranged forwardly of and alignwith the supports I'I. Each of the supports I3, I6, Il and i8 is in theform of a single upright or post.

The grandstand I2 includes a set of spaced parallel vertically disposedslidable supports i9 of inverted iJ-shape and which correspond in numberto that of the supports I8. The supports I9 are of less height than,arranged forwardly of and align with the supports I8.

The supports I6, I'I and I8 have attached to their lower ends rollers26, 2| and 22 respectively. The lower ends of the sides 23, 24 of eachsupport I9 are provided with rollers 25, 26 respectively,

Arranged between a support I3 and a support I6 which aligns with saidsupport I3 is an upstanding holder bar or intermediate vertical support2l of less height than the said supports I3, I6. Extending forwardlyfrom the said support I3 is a pair of superposed links 28, 29 pivotallyconnected at their rear ends, as at 3G, SI to the support I3 and attheir forward en-ds to the bar 21 by pivots 32, 33 respectively.Extending rearwardly from the said support I6 in proximity to the upperend of the latter is a lever or arm 34 having its forward end terminalportion 35 curved upwardly and which is pivotally connected at itsforward end as at 36 to the said support I6. The rear end of lever 34 ismounted on the pivot 32 for the link 28. Extending rearwardly from thesaid support I8 is a link 3l which has its rear end mounted on the pivot33 for the link 2S. The forward end of link 3l' is pivotally connectedto the said support I5 as at 38. Y

Arranged between a support I9 and support II which aligns with the saidsupport I6 is an upstanding holder bar 39 of less height than the saidsupports I9, i? and of less height than the bar 2'I. Extending forwardlyfrom the said support I6 is a pair of superposed links 4U, 4I pivotallyconnected at their rear ends as at 42, 43 respectively to the saidsupport IE and at their forward ends to the bar 59 by the pivots 44, 45.Extending rearwardly from the said support I'l in proximity to the upperend of the latter is a lever 4G having its forward end terminal portion41 curved upwardly and which is pivotally connected at its forward endas at 43 to the said support I'I. The rear end of lever 46 is mounted onthe pivot 44 for the link 49. Extending rearwardly from said support ITis a link 49 which has its rear end mounted on the pivot 45 for the link4I and has its forward end pivotally connected to said support I1 as at50. Arranged between a support I'I and a support I8 which aligns withthe said support I'I is an upstanding holder bar 5i of less height thansupports I'I, I8 and of less height than the bar 39. Extending forwardlyfrom the said support Il is a pair of superposed links 52, 53 pivotallyconnected at their rear ends as at 54, 55 respectively to the saidsupport Il and at their forward ends to the bar 5I by the pivots 59, 5lrespectively. Extending rearwardly from the said support I8 in proximityto the upper end of the latter is a lever 5S having its forward endterminal portion 59 curved upwardly and which is pivotally connected atits forward end as at 59 to the support I8. The rear end of lever 58 ismounted on the pivot 5G for the link 52. Extending rearwardly from thesaid support I8 is a link 6I which has its rear end mounted on the pivot5'! for the link 53 and its forward end pivotally connected to the saidsupport I8 as at 62.

Arranged between a support I8 and the side 24 of a support I9 whichaligns with the said support I8 is an upstanding holder bar 63 of lessheight than the sai-d supports I8 and I9 and of less height than the bar5I. Extending forwardly from the said support I8 is a pair of superposedlinks 64, B5 pivotally connected at their rear ends as at 66, Glrespectively to the said support I8 and at their forward ends to the bar63 by the pivots 38, G9 respectively. Extending rearwardly from the side24 in proximity to the upper end of the latter is a lever 'I9 having itsforward end terminal portion 'II curved upwardly and which is pivotallyconnected at its forward end as at 'I2 to the side 24 of the saidsupport I9. The rear end of lever 'i9 is mounted on the pivot 68 for thelink 64. Extending rearwardly from the side 24 of the said support I9 isa link 'I3 which has its rear en-d mounted on the pivot 69 for the link65 and its forward end pivotally connected to the side 24 of the saidsupport I9, as at 14.

The link 28 and lever 34 are arranged above the link 49 and lever 46.The link 52 and lever 58 are arranged below the link 40 and lever 46 andthe link 64 and lever 'H3 are arranged below the link 52 an-d lever 58.The links 29, 3'1 are arranged above the links 4I and 49. 'Ihe links 53,6I are arranged below the links 4I and 49 and the links 65, 'I3 arearranged below the links 53, 6I.

The grandstand I2 includes seat members 15, lo, TI, 'I9 and i9. Saidmembers when the grandstand is extended are positioned in a mannerwhereby member I6 is arranged below the member l5, member 'VI belowmember 16, member 'I8 below member 'I'I and member 'I9 below member 18.The lower face of member 'I5 is provided with spaced parallel dependingbrackets which are secured to the upper ends of the supports I3 wherebymember 25 is anchored to the supports I3. Said member 'I5 extendsforwardly with respect to the upper ends of the supports I3.

The lower face of member 'I6 is provided with spaced parallel dependingbrackets 8I which are secured to the upper ends of the supports I6whereby member 'I5 is anchored to the support I6. Member 'l5 extendsforwardly with respect to the upper ends of the supports I6. The lowerface of member 'H is provided with spaced parallel depending brackets 82which are secured to the upper ends of the supports I'I whereby member11 is anchored to the supports I1. Said member 11 extends forwardly withrespect to the upper ends of the supports |1. The lower face of member18 is provided with spaced parallel depending brackets 83 which aresecured to the upper ends of the supports I8 whereby member 18 isanchored to the supports I8. Said member 18 extendstforwardly withrespect to the upper ends of the supports I8. The member 19 is securedto and on the tops 84 of the supports I9. The supports I9 are securedtogether by a plank or bar 85 arranged forwardly of and suitablyanchored to the sides 23 of the said supports I9.

Secured upon and bodily carried with the levers 34 and extended on thelinks 28 when the structure is extended, is a foot board or rest 86 forthe occupants. of the seat member 15. Secured upon and bodily carriedwith the levers 46 and extended on the links 40 when the structure isextended is a foot board or rest 81 for the occupants of the seat member16. Secured upon and bodily. carried with the levers 58 and extendedupon the links 52 when the structure is extended is a foot board or rest81a for the occupants of the seat member 11, and secured upon and bodilycarried with the lever 14 and extended upon the links 64, when thestructure is extended, is a foot board or rest 81h for the occupants ofthe seat member 18. The foot rest for the occupants of the seat member15 is provided by a base, platform or flooring 88 forming an element ofthe grandstand and which will hereinafter be termed a base.

The base 88 includes a rear section 89, an intermediate section and aforward section 9 I. The section 90 is of lesslength than the section 59and the latter is of less length than the section 9|. The sections 90and 9| are foldable relatively to the section 89. The section 89 ishinged to the section 90 as at 92 and the section 90 is hinged to thesection 9| as at 93. When the grandstand is in a non-extended position,such as shown in Figure 2, the sections 90 and 9| will be arranged inthe manner as shown in Figure 2. The supports I3 permanently rest on thesection 39 of the base 88 and are ilxedly secured therewith in anysuitable manner. The ground or support upon which the grandstand ispositioned is indicated at 94.

A set of spaced parallel hinges 92 is employed for connecting thesections 89 and 90 together.

. A set of spaced parallel hinges 93 is employed for connecting sections90 and 9| together.

The base 88 lengthwise thereof has secured upon its upper face a seriesof spaced parallel tracks 94(i lengthwise thereof. The number of trackscorrespond in number to that of the supports of each set. Each trackconsists of a rear section 95, an intermediate section 96 and a forwardsection 91. When the base 98 is extended to the position shown in Figure1 the sections of each track align. The track sections 96 and 91correspond in length to the base sections 90, 9| respectively. The tracksections 95 are of less length than the base section 89. The rear endsof the track sections 91 are bevelled as at 98. The forward ends of thetrack sections 96 are bevelled as at 99 but the bevel extends in anopposite direction with respect to the bevel on the rear ends of thetrack sections 91. The rear ends of the track sections 96 are bevelleclas at |00. The forward ends of the track sections 95 are bevelled as atIOI but the bevel extends in an opposite direction with respect to thebevel on the rear ends of the track sections 96. The bevel ofthe tracksections in the manner as stated provides for them to assume theposition shown in Figure 2 when the grandstand is folded. Each of thetrack sections consists of a channel-shaped member |02 of the form shownin Figure 5. The rollers on the lower ends of the supports I6, I1, I8and |9 travel in the tracks 94. When the grandstand is in a non-extendedposition, the rollers on the lower ends of the supports I6, I1, I8 andI9 are arranged in the sections 95 of the tracks 98 and in thisconnection attention is directed to Figure 2. When the grandstand is ina non-extended position, the foot rests 86, 81, 81a, 81b are disposed onone of their lengthwise edges and the levers 34, 46, 58 and 10 arevertically arranged, such as shown in Figure 2. When the grandstand isextended, the holder bars 21, 39, 5| and 53 seat in the tracks 94. Whenthe grandstand is in a non-extended position, the links and levers arefolded upwardly and carry the holder bars therewith, and further thebase section 90 abuts the plank 85 and the base section 9| abuts theseat members 15, 16, 11 and 18. Any suitable means may be employed fordetachably connecting the base section 9| to the seat member 15.

With reference to Figures 8 to 11, the grandstand is generally indicatedat |03 and by way of example, it is shown with four seat members andthree `foot boards or rests, but it is to be understood that the numberof seat members and foot boards may be increased. However, the number ofthe seat members will be greater by one than the number of the footrests. The grandstand |03 will include a set of pairs of upstandingsupports for each seat member. The number of pairs of upstandingsupports of a set may be as desired and is shown by way of example aseach set consisting of three pairs of supports. The supports of eachpair of a set are of the same height and are arranged in parallel spacedrelation. The space between the supports of a pair is of less width thanthat of the space between the pairs of supports of a set. As shown, thegrandstand I 03 includes respectively a rear set of spaced pairs ofsupports and the supports of each pair of supports of said rear set areindicated .at |04, |65; forward and rear intermediate sets of spacedpairs of supports, the supports of each pair of supports of the rearintermediate set being indicated at |06, |01 and the supports of eachpair of supports of the forward intermediate sets are indicated at |08,|09; and a front set of spaced pairs of supports and the supports ofeach pair of supports of the front set are indicated at I|0 and I| I.'Ihe supports of a rear set are of greater height than the supports ofthe rear intermediate set. The supports of the forward intermediate setare of less height than the supports of the rear intermediate set, andthe supports of the front set are of less height than the supports ofthe forward intermediate set. The supports of the rear set arestationary. The supports of the intermediate sets are movable towardsand from the supports of the rear set. The supports of the front set arevertically movable and are shiftable towards and from the frontintermediate set. The-supports of the rear and intermediate sets align.The supports of the front set align with the supports of the other setwhen the supports of the front set are in active and inactive positions.Secured respectvely with the upper ends of and extending forwardly fromthe supports of the rear set is a seat member I 2; with the upper endsand extending forwardly from the supports l forward ends to the bar |26.

of the rear intermediate set is a seat member H3; and with the upperends of and extending forwardly from the supports of the forwardintermediate set is a seat member H4. The supports of the front set arepivotally connected with a seat member 5.

The supports of each pair of supports' of the rear set are connectedtogether by oppositely extending inclined clross braces H6 and |I1 and atransverse bar H8. The supports of each pair of supports of the rearintermediate set are connected together by oppositely extending inclinedcross braces H9, |20. The supports of each pair of supports of theforward intermediate set are connected together by oppositely extendinginclined cross braces I2 I, |22, and the supports of each pair ofsupports of the front set are connected together by a transverse brace|23.

The seat members H2, H3 and ||4 are pro vided on their lower faces withdepending spaced parallel brackets |24 which are fixed to the upperportion of the supports of the said rear and intermediate sets. The seatmember H has depending therefrom spaced blocks |25 which are anchoredtogether at their fronts by a coupling bar |26, common to all of saidblocks. Each block |25 is arranged over a pair of spaced parallel armsor levers |21, |28 anchored at their The upper ends of the supports H0,are pivotally connected as at |29 to the arms |21, |28 in proximity totheir forward ends.

Each pair of supports of the rear set is connected to a pair of supportsof the rear intermediate set. Each pair of supports of the rearintermediate set is connected to a pair of supports of the forwardintermediate set and each pair of supports of the forward intermediateset is connected to a pair of supports of the front set. The manner inwhich the aligned pairs of supports of the said sets are connectedtogether will now be referred to. Extending forwardly from the supports|04, |05 is an upper pair of straight links |30, I3| respectively andextending rearwardly from the supports |06, |01 is a pair of levers |32,|33 respectively formed with upwardly extending curved forward endterminal portions |34. Extending forwardly from the supports |04, |05 isa lower pair of curved links |35, |36 respectively and extendingrearwardly from the supports |06, |01 is a pair of straight links |31,|38 respectively. lArranged between the supports |04, |06 is anupstanding holder bar |39. Arranged between supports |05, |01 is anupstanding holder bar |40 disposed in parallel spaced relation to thebar I 39. The bars |39, in proximity to their lower ends are connectedtogether by a cross brace |4|. The rear ends of the links I 30, |3| arepivoted to the supports |04, |05 as at |42. The rear ends of the links|35, |36 are pivotally connected to the supports |04, |05 as at |43. Theend terminal portions |34 of the levers |32, |33 are pivotally connectedto the supports |06, |01 as at |44. The forward ends of the links |31,|38 are pivoted to the supports |06, |01 as at |45. The upper ends ofthe bars |39, |40 carry pivots |46 for the levers |32, |33 in proximityto the rear ends of said levers and for the forward ends of the links|30, |3|. The bars |39, |40 in proximity to their lower ends carrypivots |41 for the forward ends of the links |35, |36 and for the rearends of the links |31, |38. Extending forwardly from the supports |06,|01 are a pair of upper links |48 which are pivotally connected at theirrear ends as at |49 to the supports |06, |01. The links |48 are straightand are arranged below the levers |32, |33. Extending forwardly from thesupports |06, |01 is a pair of curved lower links |50 which arepivotally connected at their rear ends, as at |5| in proximity to thelower ends of the supports |06, |61. Extending rearwardly from thesupports |08, |09 is a pair of levers |52 having upstanding forward endterminal portions |53 pivotally connected as at |54 to the supports |08,|09. Pivotally connected to the supports |08, |09 below the levers |53as at |55 is a pair of double-arm levers |56. One of the arms of eachlever |56 is indicated at |51 and the other arm is at |58. The arms |51,|58 are disposed at opposite inclinations. The arm |51 is of less lengththan the arm |58. Arranged between the supports |05 and |08 is a holderbar |59. Arranged between the supports |01 and |09 is a holder bar |50.The bars |59, |60 are upstanding and are arranged in parallel spacedrelation. The bars |59, |60 are provided at their upper ends with pivotsi6! for the rear ends of the levers |53 and the forward ends of thelinks |48. The bars |59, |60 in proximity to their lower ends areprovided with pivots |62 for the rear ends of the arms |58 of the levers|56 and the forward ends of the links |60. The levers |32, |33 havedepending therefrom curved links |63. The upper ends of the links |63are pivotally connected, as at |64 I1 to the levers |32, |33. The lowerends of the links |63 are pivotally connected, as at |65 to the links|49.

The forward ends of the arms |51 of the levers I 56 are pivotallyconnected as at |66 to the upper ends of a pair of depending links |61.The lower ends of the links |61 are pivotally connected as at |68 to therear ends of extensions |69 formed on the rear ends of the arms |21,|28. Pivotally connected at their upper ends t0 the arms |21, I 28, asat |10, is a pair of parallel upstanding supports I1! which areconnected to the supports |08, |83 by braced coupling pieces |12.Corlynected with the supports |1| is a forwardly extending bar |13pivotally connected with the brace f |23. The lower ends of the supports|06, |01, |08, |09 and |1| are provided with rollers |15 which travel intracks to be referred to. Secured at its upper end to the cross brace H8and at its lower end to the cross brace |4| is a depending for- ,-f

|11 for the occupants of the seat member H2.

Secured upon the levers |52, and extending upon the links |48 is a footboard or foot rest |18 for the occupants of the seat member H3. Securedupon the arms |21, |28 and projecting upon the extensions |69 is a footboard or foot rest |19 for the occupants of the seat member I4. The footrest for the occupants of the seat member |I5 is provided by a base,platform or flooring forming an element of the grandstand and which willhereinafter be termed a base.

The base |80 includes a rear section I8I; an intermediate section |82and a forward section |83. The base |80 is of the same form as the base88 with the exception that the forward section is provided with areleasable latching structure |84 for coaction with the keeper |85carried by the seat member H2 for the purpose of latching the forwardsection of the base to seat member H2 when the grandstand is innon-extended or folded position, such as shown in Figure 8. Secured 'Silupon the upper face of the base are sectional tracks |86 correspondingin number' to the number of supports of a set. The tracks |86 areconstructed in the same manner as the tracks |02 referred to inconnection with the structure shown by Figures 1 and 2. When thegrandstand |03 is extended the supports I I0, I I I are arrangedforwardly of the tracks |86. 'I'he rollers |75 carried by the supports|06, |01, |08, |09 and |1| travel in the tracks |86. The lower ends ofthe supports |04, IE5 are provided with braced coupling pieces |81 whichare anchored to the section |8| of the base |80.

When the grandstand |03 is folded, it will assume the position as shownin Figure 8. The sections of the base |30 are hinged together in thesame manner as the sections of the base 88.

It will be seen that in either form of the grand stand, all of theforward seat members are folded compactly below the rearmost seatmember. 'I'his makes it possible to nest the seat members in arelatively small space. Furthermore, it will be seen that the weight ofthe seat members is never lifted from the base, but at all timessupported by the supports which carry them, moving rectilinearly uponthe track sections and thus there is no danger of the seat membersfalling down due to broken springs or defective parts. When a grandstandis folded up all of the forward supports for the seat members areshifted rearwardly towards the rearmost supports for the seat membersand which is due to the moving upwardly and rearwardly respectively ofthe intermediate and forward base sections. On the lowering of theforward and intermediate base sections, the seating structure isextended to the position shown in Figure 1 or 10.

The link and lever mechanisms between one set of supports and anadjacent set of supports are termed coupling structures which functionas foot rests or foot board supports. These latter are foldable with thecoupling structures.

Each grandstand includes a group of spaced parallel sets of upstandingsupports, the sets of said group progressively increasing in height fromthe front to the rear of the group.

The base of the grandstand is so constructed that the forward andintermediate sections thereof are foldable relatively to each other andto the rear section of the base.

What I claim is:

In a foldable and extendible seating structure, a group of upstandingopposed bodily shiftable sets of spaced slidably mounted supports, anupstanding set of spaced stationary supports opposing the rear set ofsaid group, a continuous seat forming member secured upon the upper endsof the supports of each set, sets of spaced levers having straight rearparts and upturned front parts, the front parts being pivotallyconnected at their forward ends to one side of the forward sets ofsupports below the seat members, sets of forwardly extending upper linkshaving their rear ends pivotally connected to one side of the rear setsof supports below the seat members, sets of rearwardly extending forwardlower links pivotally connected to said side of the forward sets ofsupports in proximity to the lower ends of the latter, sets of forwardlyextending rear lower links having their rear ends pivotally connected tosaid side of the rear sets of supports in proximity to the lower ends ofthe latter, sets of upstanding bars aligning with the supports of saidsets and pivotally connected respectively at one side of their upperends to one side of the rear parts of said sets of levers and to oneside of the upper sets of links and at said side thereof in proximity totheir lower ends to one side of the sets of lower forward and lower rearlinks, and continuous foot rest members, `each having the major portionof its width fixedly secured on the rear parts of a set of levers, theremaining portion of its width of each foot rest member seating on theforward end terminal portions of an upper set of links when

